System connectors associated with cellular telephones are used to establish and maintain electrical connection between the internal circuitry of the telephone and an external electrical circuit or device. Examples of such external devices and connection requirements are battery charging equipment and base or docking stations typically employed in automobiles to permit hands-free operation of the cellular telephone unit. In the case of charging units, the telephone unit must incorporate external electrical power contacts that provide access to the associated on-board battery pack. The ability to dock with a hands-free base station requires, at a minimum, that the telephone unit incorporate sufficient external electrical contacts to facilitate transfer of the necessary data from the internal circuitry of the telephone unit to the associated base station.
Historically, such system connectors presented openings or pathways for water and debris to freely enter the interior compartment of the telephone. Typically, these penetration pathways are present in the telephone unit because there are several separate components, including a printed circuit board, a structural frame member, and a housing enclosure that must be assembled, none of which are sealed prior to assembly. As such, system connectors are generally comprised of separate pieces that are either soldered directly to the printed circuit board or are pressed onto the printed circuit board with the housing and frame aligning around them.
In addition to the concerns for totally sealing the cellular telephone, it is also desirable to provide a system connector that can be easily and efficiently electrically coupled to the printed circuit board. Typically, system connectors, sometimes herein referred to as external connectors, are often connected to the printed circuit board by hand or reflow soldering. In some instances, the external connector is attached to the front cover of the cellular telephone with an adhesive and then the external connector and the printed circuit board are interconnected with a flex film assembly. There are shortcomings and drawbacks to both of these approaches. With respect to hand soldering, this is expensive because most operations are done manually. Further, yields tend to be low due to operator error and the varying skill levels found among workers. Reflow soldering operations are difficult to manage because of the large size of the external connector. With respect to utilizing a flex film assembly, this approach adversely affects the overall size of the cellular telephone. In the end, the flex film assembly requires more space and that translates into a larger cellular telephone. In addition, it is expensive to assemble flex film because flex film assemblies are not generally automatable. Finally, utilizing an approach where the external connector is permanently attached to the printed circuit board results in additional tolerance concerns between the external connector contact and the housing of the cellular telephone. This adversely affects the tolerance stack up between accessories that attach to the housing of the cellular telephone and their mating system connector contacts. In the end, overall component tolerances must be held tighter, and this, of course, increases cost. As a result, one finds that the overall package design of the cellular telephone suffers. To accommodate these large tolerances, the packaging size of the cellular telephone necessarily increases.
Therefore there remains the need for a waterproof or sealed system connector for cellular telephone units that can be manufactured and implemented easily and inexpensively, which eliminates the risk of moisture penetration and subsequent damage to the internal electrical components that comprise the telephone. In addition, there is a need for a system connector design that forms an integral part of the housing structure of the cellular telephone which is capable of automated assembly, with the system connector being designed to interface with the printed circuit board through pressure contacts rather than soldered contacts.